1. Field of the Invention
The invention relates to pipe flanges. In particular, the invention relates to pipe flanges used in high pressure petroleum and natural gas production.
2. Description of the Related Art
Erosion and corrosion of the interior of high pressure steel pipe by the fluids flowing therethrough commonly occurs in the vicinity of the weld joint joining smaller diameter pipe to larger diameter pipe in which fluids are flowing from the smaller diameter pipe to the larger diameter pipe. The fluids flowing through such pipe may be under high pressures from 50 pounds per square inch to 10,000 pounds per square inch or more and have very high velocity flowing through the pipe and may have corrosive and abrasive elements therein. Such pressures are commonly encountered when natural gas, petroleum, and associated fluids are flowing out of deep gas and petroleum wells.
Such erosion requires constant monitoring and periodic replacement of welded metal pipe joints and flanges of such pipelines to prevent rupture of the pipeline due to erosion. Periodic replacement of welded pipe joints and flanges to prevent pipeline rupture due to erosion is expensive, sometime dangerous to personnel making the replacement, and commonly requires the interruption of flow through the pipeline. Rupture of such pipelines can cause serious injury or death of personnel in the area of the rupture, explosions, catastrophic damage to equipment, loss of expensive petroleum and gas, and serious pollution of the environment.
Elimination or reduction of the erosion of such pipe joints and flanges in high pressure pipelines is therefore highly desirable.
Exemplary of the Patents of the related art are the following U.S. Pat. Nos.: 2,290,333; 2,310,927; 2,354,900; 2,806,718; 2,982,311; 3,018,120; 3,228,096; 3,235,291; 3,284,107; 3,284,108; 4,277,091; 4,691,740 and 4,995,427.